The long term goals of this project are to characterize the role of central corticotropin releasing factor (CRF) systems in physiology and behavior under chronic stress conditions. The CRF system has recently been recieving increasing attention for its role in coordinating behavioral, autonomic and endocrine responses to stress. Changes in central CRF activity has been linked to stress-related disorders such as depression, post-traumatic stress disorder, and anxiety disorders. While it is well known that chronic stress is associated with the onset of stress related disorders such as depression, little is known regarding changes in central CRF systems under chronic stress conditions. The specific aims of this project are to examine CRF receptor expression in the neural circuitry that may underlie chronic stress responses using insitu hybridization. Secondly, this project aims to investigate which sites within this circuitry mediate differential effects of CRF receptor antagonists on stress-induced anxiety behavior as well as on activity in the stress-sensitive hypothalamic-pituitary-adrenal axis. Lasty, we aim to examine corticosterone-mediated regulation of CRF receptors in the circuitry underlying chronic sress responses after acute and chronic stress.